ZNF554 Inhibits Endometrial Cancer Progression via Regulating RBM5 and Inactivating WNT/β-Catenin Signaling Pathway

Objective: Uterine corpus endometrial carcinoma (UCEC), a kind of gynecologic malignancy, poses a significant risk to women's health. The precise mechanism underlying the development of UCEC remains elusive. Zinc finger protein 554 (ZNF554), a member of the Kruppel-associated box domain zinc finger protein superfamily, was reported to be dysregulated in various illnesses, including malignant tumors. This study aimed to examine the involvement of ZNF554 in the development of UCEC. Methods: The expression of ZNF554 in UCEC tissues and cell lines were examined by qRT-PCR and Western blot assay. Cells with stably overexpressed or knocked-down ZNF554 were established through lentivirus infection. CCK-8, wound healing, and Transwell invasion assays were employed to assess cell proliferation, migration, and invasion. Propidium iodide (PI) staining combined with fluorescence-activated cell sorting (FACS) flow cytometer was utilized to detect cell cycle distribution. qRT-PCR and Western blotting were conducted to examine relative mRNA and protein levels. Chromatin immunoprecipitation assay and luciferase reporter assay were used to explore the regulatory role of ZNF554 in RNA binding motif 5 (RBM5). Results: The expression of ZNF554 was found to be reduced in both UCEC samples and cell lines. Decreased expression of ZNF554 was associated with higher tumor stage, decreased overall survival, and reduced disease-free survival in UCEC. ZNF554 overexpression suppressed cell proliferation, migration, and invasion, while also inducing cell cycle arrest. In contrast, a decrease in ZNF554 expression resulted in the opposite effect. Mechanistically, ZNF554 transcriptionally regulated RBM5, leading to the deactivation of the Wingless (WNT)/beta-catenin signaling pathway. Moreover, the findings from rescue studies demonstrated that the inhibition of RBM5 negated the impact of ZNF554 overexpression on beta-catenin and p-glycogen synthase kinase-3 beta (p-GSK-3 beta). Similarly, the deliberate activation of RBM5 reduced the increase in beta-catenin and p-GSK-3 beta caused by the suppression of ZNF554. In vitro experiments showed that ZNF554 overexpression-induced decreases in cell proliferation and migration were counteracted by RBM5 knockdown. Additionally, when RBM5 was overexpressed, it hindered the improvements in cell proliferation and migration caused by reducing the ZNF554 levels. Conclusion: ZNF554 functions as a tumor suppressor in UCEC. Furthermore, ZNF554 regulates UCEC progression through the RBM5/WNT/beta-catenin signaling pathway. ZNF554 shows a promise as both a prognostic biomarker and a therapeutic target for UCEC.